Parts. I acquired the following parts: • One N20 6VDC 30RPM gear motor. • One twin AAA battery case with switch. • Two AAA batteries. • Four 12MM diameter by 2.5MM thick neodymium magnets. • One 11mm diameter "nylon solid plastic bearing balls G1 precision". • One 200CM by 120CM by 1.5CM thick marble slab (actually, I "borrowed" my wife's marble cheese board but don't tell her!). I 3D printed the following parts at .15mm layer height and 20% infill in PLA unless noted otherwise: • One "Arm.stl", .15mm layer height, 100% infill, Tough PLA. • One "Axle.stl". • One "Base.stl". • One "Funnel.stl". • One "Wheel.stl", .15mm layer height, 100% infill, Tough PLA. The model also uses threaded assembly thus an M8 by 1.25 tap and die will assist with thread cleaning if necessary. Assembly. To assemble the model, I performed the following steps: • Soldered the battery pack wires to the gear motor such that with power applied the gear motor shaft rotated clockwise. • Pressed the gear motor into the motor mount in "Base.stl". • Pressed "Wheel.stl" onto the motor shaft. • Pressed "Funnel.stl" onto the base assembly making certain the slots in the funnel aligned with the slots in the base. • Pressed two magnets into the magnet pocket in the base such that the magnets were flush with the front of the model. • Pressed two magnets into the magnet pocket in "Arm.stl" matching the polarity of the base magnets. • Secured the arm assembly to the base assembly using "Axle.stl", making certain the arm rotated smoothly. • Secured the mechanism and battery case to the marble slab using double sided tape. With assembly complete, I placed the model on a flat and level surfaced, placed the nylon ball bearing in the funnel, turned on the battery switch, and off the marble flew! And that is how I 3D printed and assembled "Marblevator, Marble Launch Mechanism". I hope you enjoyed it!